No abstract

The time course of formation of lysine N‐hydroxylase and N‐transacetylase in Escherichia coli bearing cloned genes derived from pColV‐K311 was followed and the influence of iron concentration on the enzyme induction was studied. Specific activities of both enzymes were determined for 8 strains prepared by Braun and coworkers [1,2] comprising the separated genes on the vectors pBR322 or pACYC184. The assignment of genes aerA and aerB to the first two enzymes of aerobactin biosynthesis [2] was confirmed. The active enzyme encoded by aerA (N‐hydroxylase) has an Mr of 52 000 and that of aerB (N‐transacetylase) an Mr of 70 000, as determined by gel filtration. The Mr of the N‐transacetylase was 35 000 in sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE).